How to subsurf this wing without adding vertices to its profile (only to the curvature)
Beveling Edge Loop:

Choose Edge Select mode and select desired Edge Loops (like you have in your screenshot now) then hit Ctrl+B to Bevel, you can set amount of Edge Loops by hand (mouse scroll and move) or just by tweaking values in Tools Panel or by pressing F6.



Loft with LoopTools:

This method will allow you to add the same number of Loops between existing ones. You need to turn on LoopTools addon in User Preference menu.

Select all Edges between Loops, delete them, then select remaining Edge Loops, hit W > LoopTools > Loft and change values accordingly.

Sadly there is not (or I'm not aware of it) any automatic method to give same space between all Edge Loops given that there is different space with existing ones. You can just put same amount of cuts. As a workaround you can make two things. First one is kind a eye-balling, so it's not perfect.



Spacing Manually by Loop Cuts:

In this method you will need to place Loop Cuts (Ctrl+R > MouseScroll) manually and eye-balling number of cuts. It could give pretty nice result with a little of practice.



Dissolving and adding new cuts:

This one is a last option, this will give even spacing but will not preserve main shape and you will need to manually move Edge Loops with Proportional Editing turned on.

Select existing Edge Loops, Dissolve Edges, add Loop Cuts, move new Edge Loops with Proportional Editing turned on (MouseScroll to control influance).